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https://github.com/coshx/caravel

A Swift event bus for UIWebView/WKWebView and JS.
https://github.com/coshx/caravel

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A Swift event bus for UIWebView/WKWebView and JS.

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![Caravel Logo](https://raw.githubusercontent.com/coshx/caravel/master/logo.png)

[![CocoaPods](https://img.shields.io/cocoapods/v/Caravel.svg?style=flat-square)](https://cocoapods.org/pods/Caravel)

[![Join the chat at https://gitter.im/coshx/caravel](https://img.shields.io/gitter/room/nwjs/nw.js.svg)](https://gitter.im/coshx/caravel?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)

**An event bus for sending messages between UIWebView/WKWebView and embedded JS. Made with pure Swift.**

## Features

* Easy, fast and reliable event bus system
* Multiple bus support
* Multithreading support
* `WKWebView` support
* iOS ~> JavaScript supported types:
- `Bool`
- `Int`
- `Float`
- `Double`
- `String`
- Any array (using types in this list, including dictionaries)
- Any dictionary (using types in this list, including arrays)
* JavaScript ~> iOS supported types:
- `Boolean`
- `Int`
- `Float` (available as a `Double`)
- `String`
- `Array` (available as a `NSArray`)
- `Object` (available as a `NSDictionary`)

## Installation

### Using CocoaPods

Add this line to your Podfile:

```ruby
pod 'Caravel'
```

And run `pod install`. Once installed, open the `Pods` folder. Navigate to `caravel/caravel/js`. In this folder, drag and drop `caravel.min.js` into your Xcode project. You should load this JS script in any webpage you use Caravel.

### Using Carthage

Add this line to your Cartfile:

```
github "coshx/caravel"
```

And run `carthage update`. Once installed, open the `Carthage/Checkouts` folder. Navigate to `caravel/caravel/js`. In this folder, drag and drop `caravel.min.js` into your Xcode project. You should load this JS script in any webpage you use Caravel.

### Using as a submodule

Clone this repo and add `Caravel.xcodeproj` into your workspace.

## Might be useful

* [Engineer a TODO list using Caravel and Framework7](http://www.coshx.com/blog/2015/12/04/engineer-a-todo-list-using-caravel-and-framework7/)
* [Migrate from 0.* to 1.*](http://www.coshx.com/blog/2015/11/19/releasing-caravel-1-0-0/)

## Get started

Caravel allows developers to communicate between their `UIWebView` and the embedded JS. You can send any kind of message between these two folks.

Have a glance at this super simple sample. Let's start with the iOS part:

```swift
class MyController: UIViewController {
@IBOutlet weak var webView: UIWebView!

override func viewDidLoad() {
super.viewDidLoad()

// Prepare your bus before loading your web view's content
Caravel.getDefault(self, webView: webView, whenReady: { bus in
// In this scope, the JS endpoint is ready to handle any event.
// Register and post your events here
bus.post("MyEvent", data: [1, 2, 3])

self.bus = bus // You can save your bus for firing events later
})

// ... Load web view's content there
}
}
```

And now, in your JS:

```javascript
var bus = Caravel.getDefault();

bus.register("AnEventWithAString", function(name, data) {
alert('I received this string: ' + data);
bus.post("AnEventForiOS");
});
```

And voilà!

## WKWebView

Caravel 1.1.0 supports `WKWebView`. Keep in mind this component is still in beta and might not work as expected. We won't ship you a 🍕 if your app does not work.

Anyway. If you're this kind of guy who likes being involved in some risky business, here is an example about how to use Caravel with it. Be careful, it is a 2-step process.

```swift
class MyController: UIViewController {
private var wkWebView: WKWebView?

override func viewDidLoad() {
super.viewDidLoad()

let config = WKWebViewConfiguration()
// First generate a draft using your custom configuration
let draft = Caravel.getDraft(config)

// Build your WKWebView as usual then
self.wkWebView = WKWebView(frame: self.view.bounds, configuration: config)

// Finally initiate Caravel
Caravel.getDefault(self, wkWebView: self.wkWebView!, draft: draft, whenReady: {
// Do whatever you've got to do here
})

// ... Load content into your WKWebView there
}
}
```

## Porting your app from Drekkar to Caravel

Super duper easy. Just use the same codebase and use the JS script from Caravel. Finally, add this after having loaded the Caravel script:

```javascript
var Drekkar = Caravel;
```

## Troubleshooting

### 😕 Sometimes the bus is not working?!

Firstly, ensure you are using the bus correctly. Check if you are unregistering the bus when exiting the controller owning your web component (either a `UIWebView` or a `WKWebView`). Use the [unregister method for this](http://coshx.github.io/caravel/Classes/EventBus.html#/s:FC7Caravel8EventBus10unregisterFS0_FT_T_).

Caravel automatically cleans up any unused bus when you create a new one. However, this operation is run in the background to avoid any delay on your side. So, a thread collision might happen if you have not unsubscribed your bus properly.

However, if you think everything is good with your codebase, feel free to open a ticket.

### I want to use my custom UIWebViewDelegate. What should I do?

To raise iOS events, Caravel must be the delegate of the provided `UIWebView`. However, if there is any existing delegate, Caravel saves it before setting its own. So, if you would like to use your custom one, simply set it **before** any call to Caravel.

### I want to use my custom WKUserContentController. What should I do?

To raise iOS events, Caravel adds a custom `WKScriptMessageHandler` to the current content controller. If you would like to use your custom one, simply set it **before** any call to Caravel.

### What object should I use as a subscriber?

A subscriber could be any object **except the watched target** (either the `UIWebView` or the `WKWebView`). We recommend to use the controller as a subscriber (it is a common pattern).

### Reserved names

`CaravelInit` is an internal event, sent by the JS part for triggering the `whenReady` method.

Also, the default bus is named `default`. If you use this name for a custom bus, Caravel will automatically switch to the default one.

Finally, when using a `WKWebView`, Caravel names its script message handler `caravel`.

### Keep in mind event and bus names are case-sensitive.